Abstracts

INTRODUCTION

The basement underlying the Neoproterozoic covers in the region of Corumba has been described as part of the Rio Apa Complex (Rio Apa Terrane) which consists of metagranites, orthognaisses, and subordinate amphibolites (Godoi et al. 2001Godoi H.O., Martins E.G., Mello J.C.R., Scislewski G. 2001. Programa de Levantamentos Geológicos Básicos do Brasil - PLGB: folha SE.21-Y-D - Corumbá; Folha SF.21-V-B- Aldeia Tomázia; Folha SF.21-V-D - Porto Murtinho: escala 1:250 000. Brasília, CPRM, 88 p.).

Several papers have shown the occurrence of Orosirian magmatism over an extensive area in southern Amazon Craton being recognized in the Rio Apa Terrane by Correia Filho et al. (1981)Correia Filho F.C.L, Martins E.G., Araújo E.S. 1981. Projeto Rio Apa: Relatório da área I. Goiânia: CPRM, Convênio CODESUL/CPRM, v. 2., Araújo et al. (1982)Araújo H.J.T., Santos Neto A., Trindade C..H., Pinto J.C.A., Montalvão R.M.G., Dourado T.D.C., Palmeira R.C.B., Tassinari C.C.G. 1982. Folha SF. 21 - Campo Grande. In: Brasil. Ministério das Minas e Energia. Projeto RADAMBRASIL - Geologia, 28:23-124., Godoi et al. (2001)Godoi H.O., Martins E.G., Mello J.C.R., Scislewski G. 2001. Programa de Levantamentos Geológicos Básicos do Brasil - PLGB: folha SE.21-Y-D - Corumbá; Folha SF.21-V-B- Aldeia Tomázia; Folha SF.21-V-D - Porto Murtinho: escala 1:250 000. Brasília, CPRM, 88 p., Lacerda Filho et al. (2006)Lacerda Filho J.W., Brito R.S.C., Silva M.G., Oliveira C.C. De, Moreton L.C., Martins E.G., Lopes R.C., Lima T.M., Larizzatti J.H., Valente C.R. 2006. Geologia e Recursos Minerais do Estado de Mato Grosso do Sul. Programa integração, atualização e difusão de dados de geologia do Brasil. Convênio CPRM/SICME - MS, MME, 10. 28 p., Cordani et al. (2010)Cordani U.G., Teixeira W., Tassinari, C.C.G., Ruiz A.S. 2010. The Rio Apa Craton in Mato Grosso do Sul (Brazil) and Northern Paraguay geochronological evolution, correlations and tectonic implications for Rodinia and Gondwana. American Journal of Science, 310:1-43., Brittes et al. (2013)Brittes A.F.N., Sousa M.Z.A.M., Ruiz A.S., Batata E.F., Lafon J.M., Plens D.P. 2013. Geologia, petrologia e geocronologia (Pb-Pb) da Formação Serra da Bocaina evidências de um Arco Magmático Orosiriano no Terreno Rio Apa, sul do Cráton Amazônico. Brazilian Journal of Geology, 43(1):48-69. and Plens et al. (2013)Plens D.P., Ruiz A.S., Sousa M.Z.A.M., Batata E.F., Lafon J.M., Brittes A.F.N. 2013. Batólito Cerro Porã: granito tipo-A pós-orogênico do arco magmático Amoguijá - Terreno Rio Apa - sul do Cráton Amazônico. Brazilian Journal of Geology, 43(3):515-534.. Vargas-Mattos (2010)Vargas-Mattos G.L. 2010. Caracterização geocronológica e geoquímica dos granitos proterozoicos: implicação para a evolução crustal da borda SW do Cráton Amazônico na Bolívia. Tese de Doutorado, Faculdade de Geologia, Universidade do Estado do Rio de Janeiro, 164 p. also describe the occurrence of Orosirian calc-alkaline granitoids in the San Pablo Terrane in Bolivia.

This work aims the understanding of magmatic and deformational evolution of the Taquaral Granite, and consequently of the Orosirian magmatism in the southern Amazon Craton. Therefore, geologic and petrographic characterization were carried out as well as SHRIMP zircon U-Pb dating, geochemistry and Sm-Nd isotopic analyses in order to determine the petrogenesis, time of emplacement, and tectonic setting.

MATERIALS AND METHODS

Twenty four samples were collected from the Taquaral Granite; among them four samples of enclaves and eight samples of diabase dikes.

Macroscopic and microscopic studies were carried out for petrographic characterization. Modal analysis by point-counting was performed on medium- to coarse-grained samples in which the selective staining technique of feldspars was previously applied according to Hutchinson (1974)Hutchinson C.S. 1974. Laboratory handbook of petrographic techniques. New York: John Wiley & Sons. 527 p.; while microscopic point-counting was performed on fine-grained samples.

The software Open Stereo was used for structural data analysis (Grohmann et al. 2011Grohmann C.H., Campanha G.A.C., Soares Junior A.V. 2011. OpenStereo: um programa livre e multiplataforma para análise de dados estruturais. In: Simpósio Nacional de Estudos Tectônicos, 13, Atas, p. 26-28.) and the shear zone rocks were classified according to Sibson (1977)Sibson R.H. 1977. Fault rocks and fault mechanisms. Journal of the Geological Society, 133:191-213..

Geochemical studies were carried out on nine samples of the Taquaral Granite, taking into consideration their spatial distribution and mineralogical and grain size diversity. Samples were prepared and then sent to the Acme Analytical Laboratories (Acmelab) in Vancouver, Canada, for major, minor and trace elements analyses (Tab. 1) by Inductively Coupled Plasma Emission Spectrometry (ICP-ES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS).

The procedure for (SHRIMP) zircon U-Pb geochronology of sample RM-07 followed the steps of sieving into 250, 210, 177, 125, 90 and 63 μm size fractions, and separation by magnetic susceptibility and density. A total of 150 zircon crystals were then hand-picked from the 177 - 125 mm size fraction, under a binocular microscope, among which the crystals for analysis were selected. Cathodoluminescence imaging (SEM-CL) and U-Pb geochronology were carried out at the Center for Geochronological Research of the University of Sao Paulo (CPGeo-IGC/USP). The analytical procedures for U-Pb zircon dating by SHRIMP II (Sensitive High Resolution Ion Microprobe) are described in details by Stern (1998)Stern R.A. 1998. High-resolution SIMS determination of radiogenic trace-isotopic ratios in minerals. In: Cabri, L.J., Vaughan, D.J (Eds). Modern approaches to ore and environmental mineralogy. Mineralogical association of Canada. Short Course Series, 27:241-268., Williams (1998)Williams I. 1998. U-Th-Pb geochronology by ion microprobe, In: McKibben M.A., Shanks III W.C., Ridley W.I., (eds), Applications of microanalytical techniques to understanding mineralizing processes. Reviews in Economic Geology, 7:1-35. and Sato et al. (2008)Sato K., Basei M.A.S., Siga O.J., 2008. Novas técnicas aplicadas ao método U-Pb no CPGeo - IGc/USP: avanços na digestão química, espectrometria de massa (TIMS) e exemplos de aplicação integrada com SHRIMP. In: Geol. USP Série Científica, 8:77-99.. Age calculations were performed using the software ISOPLOT/EX (Ludwig 2001Ludwig K.R. 2001. User's manual for Isoplot/Ex. rev., 2.49. A Geochronological Toolkit for Microsoft Excel. Berkeley Geochronological Center. 45 p. (Special Publication 1A))

Sm-Nd whole rock analyses were performed on two samples (RM-07 and RM-09A) at the Isotope Geology Laboratory of the Federal University of Para (Para-Iso), according to the analytical procedure described by Oliveira et al. (2008)Oliveira E.C., Lafon J.M., Gioia S.M.C.L., Pimentel M.M. 2008. Datação Sm-Nd em rocha total e granada do metamorfismo granulítico da região de Tartarugal Grande, Amapá Central. Revista Brasileira de Geociências, 38 (1): 114-127. and Barreto et al. (2014)Barreto C.J.S., Lafon J.M., Rosa-Costa L.T., Lima E.F. 2014. Palaeoproterozoic (~1.89 Ga) felsic volcanism of the Iricoumé Group, Guyana Shield, South America: geochemical and Sm-Nd isotopic constraints on sources and tectonic environment . International Geology Review, 56:1332-1356.. Approximately 100 mg of pulverized sample were dissolved into Teflon^(r) bombs by adding HNO₃, HCl e HF and placing them into a microwave oven. A ¹⁴⁹Sm/¹⁵⁰Nd tracer was previously introduced in order to determine the concentrations of Sm and Nd by isotope dilution. Chemical separation was made by ion-exchange chromatography divided into two stages with resins Biorad DOWEX(tm) AG50x8 and Ln Eichrom^(r). Isotopic analyses were carried out using inductively plasma mass spectrometry (ICP-MS), ThermoFinnigan Neptune. Nd-isotopic ratios were corrected for mass fractionation by normalizing to ¹⁴⁶Nd/¹⁴⁴Nd = 0.7219. The decay constant used was 6.54 x 10^-12 year^-1 (Lugmair & Marti 1978Lugmair G.W. & Marti K. (1978). Lunar initial 143Nd/144Nd: differential evolution of the lunar crust and mantle. Earth and Planetary Science Letters, 39:349-357.). Model ages were calculated according to the depleted mantle curve through time by De Paolo (1981)De Paolo D.J 1981 . Trace elements and isotopic effects of combined wallrock assimilation and fractional crystallization. Earth and Planetary Science Letters, 53:189-202..

REGIONAL GEOLOGIC SETTING

The Amazon Craton represents one of the main Precambrian geotectonic entities located on the northern part of South America platform. It consists of two shields divided by the Amazon Basin: The Central Brazilian Shield and the Guyana Shield. This work adopted the proposal of Ruiz (2005)Ruiz A.S. 2005. Evolução geológica do sudoeste do Cráton Amazônico região limítrofe Brasil-Bolívia - Mato Grosso. Tese de Doutorado, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista, 14-245 p., who considers the Rio Apa Province as a part of the compartimentation suggested by Tassinari and Macambira (2004)Tassinari C.G.C. & Macambira M.J.B. 2004. A Evolução Tectônica do Cráton Amazônico. In: Neto-Mantesso V., Bartorelli A, Carneiro C. D. R., Brito-Neves, B.B. (eds). Geologia do Continente Sul-Americano: Evolução da Obra de Fernando Flávio Marques de Almeida, p. 471-486. and revised by Cordani et al. (2009)Cordani U.G., Teixeira W., D´Agrella M.S., Trindade R.I. 2009. The position of the Amazonian Craton in supercontinents. Gondwana Research, 15:396-407., in which the Amazon Craton is divided into geochronological provinces formed by successive accretion of juvenile crust to Proterozoic mobile belts (Provinces Maroni-Itacaíunas - 2.20 to 1.95 Ga; Ventuari-Tapajós - 1.95 to 1.80 Ga, Rio Negro-Juruena - 1.80 to 1.55 Ga, Rondonian-San Ignacio - 1.50 to 1.30 Ga and Sunsas-Aguapei - 1.15 to 0.90 Ga) surrounding an Archean proto-craton (Central Amazon Province - > 2.3 Ga).

There are two proposals for the geotectonic settings of Rio Apa Terrane. The first one describes this Terrane as an allochthonous crustal fragment geographically separated from the Amazon Craton by the Tucavaca Belt (Barros et al. 1982Barros A.M., Silva R.H., Cardoso O.R.F.A., Freire F.A., Souza Jr. J.J., Rivetti M., Luz, D.S., Palmeira R.C., Tassinari C.C.G.1982. Folha SD. 21, Cuiabá. In: Brasil. Ministério das Minas e Energia. Projeto RADAMBRASIL - Geologia, 26:25-192., Del'Arco et al. 1982Del'Arco J.O., Silva R.H., Tarapanoff I., Freire F.A., Pereira L.G.M., Souza S.L., Luz J.S., Palmeira R.C.B., Tassinari, C.C.G. 1982. Geologia. In: Brasil. Ministério das Minas e Energia, Projeto RADAMBRASIL, Folha SE.21. Corumbá e Parte da Folha SE 20. Geologia, 27:25-160., Litherland et al. 1986Litherland M., Annells R.N., Appleton J.D., Berrangé J.P., Bloomfield K., Burton C.C.J., Darbyshire D.P.F., Fletcher C.J.N., Hawkins M.P.,. Klinck B.A, Lanos A., Mithcell W.I., O Connor E.A., Pitfield P.E.J., Power G.E., Webb B.C. 1986. The Geology and Mineral Resources of the Bolivian Precambrian Shield. British Geological Survey. Overseas Memoir 9. London: Her Majesty's Stationery Office. 140 p., Alvarenga & Saes 1992Alvarenga C.J.S. & Saes G.S. 1992. Estratigrafia e Sedimentologia do Proterozoico Médio e Superior da região Sudeste do Cráton Amazônico. Revista Brasileira de Geociências, 22:493-499., Brito Neves et al. 1995Brito Neves B.B., Sá J.M., Nilson A.A., Botelho N.F. 1995. A Tafrogênese Estateriana nos Blocos Paleoproterozoicos da América do Sul e processos subsequentes. Geonomos, 3:1-21., Trompette et al. 1998Trompette R., Alvarenga C.J.S., Walde D. Geological evolution of the Neoproterozoic Corumbá graben system (Brazil) 1998 . Depositional context of the stratified Fe and Mn ores of the Jacadigo Group. Journal of South American Earth Sciences, 11:587-597., Tassinari & Macambira 1999Tassinari C.C.G. & Macambira, M.J.B. 1999. Geochronological provinces of the Amazonian Craton. Episodes, 38:174-182., 2004Tassinari C.G.C. & Macambira M.J.B. 2004. A Evolução Tectônica do Cráton Amazônico. In: Neto-Mantesso V., Bartorelli A, Carneiro C. D. R., Brito-Neves, B.B. (eds). Geologia do Continente Sul-Americano: Evolução da Obra de Fernando Flávio Marques de Almeida, p. 471-486., Santos et al. 2000Santos J.O.S., Hartmann L.A., Gaudette H.E., Groves D.I., Mcnaughton N.J., Fletcher I.R. 2000. A new understanding of the Amazon Craton Provinces based on integration of field mapping and U-Pb and Sm-Nd Geochronology. Gondwana Research, 3:453-488., 2008Santos J.O.S., Rizzotto G.J., Potter P.E., McNaughton N.J., Matos R.S., Hartmann L.A., Chemale Jr. F., Quadros M.E.S. 2008. Age and autochthonous evolution of the Sunsás Orogen in West Amazon Craton based on mapping and U Pb geochronology. Precambrian Research, 165:120-152., Teixeira et al. 2010Teixeira W., Geraldes M.C., Matos R., Ruiz A.S., Saes G., Vargas Mattos G 2010 . A review of the tectonic evolution of the sunsás belt. SW Amazonian Craton. Journal of South American Earth Sciences, 29:47-60., Bettencourt et al. 2010Bettencourt J.S, Leite Jr W.B., Ruiz A.S., Matos R., Payolla B.L., Tosdal R.M. 2010. The Rondonian-San Ignácio Province in the SW Amazonian Craton: an overview . Journal of South American Earth Sciences, 29:28-46.). The second proposal, by Ruiz et al. (2005)Ruiz A.S. 2005. Evolução geológica do sudoeste do Cráton Amazônico região limítrofe Brasil-Bolívia - Mato Grosso. Tese de Doutorado, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista, 14-245 p., Lacerda Filho et al. (2006)Lacerda Filho J.W., Brito R.S.C., Silva M.G., Oliveira C.C. De, Moreton L.C., Martins E.G., Lopes R.C., Lima T.M., Larizzatti J.H., Valente C.R. 2006. Geologia e Recursos Minerais do Estado de Mato Grosso do Sul. Programa integração, atualização e difusão de dados de geologia do Brasil. Convênio CPRM/SICME - MS, MME, 10. 28 p. and Cordani et al. (2010)Cordani U.G., Teixeira W., Tassinari, C.C.G., Ruiz A.S. 2010. The Rio Apa Craton in Mato Grosso do Sul (Brazil) and Northern Paraguay geochronological evolution, correlations and tectonic implications for Rodinia and Gondwana. American Journal of Science, 310:1-43., takes into consideration the previous proposal of Almeida (1967)Almeida F.F.M. 1967. Origem e evolução da plataforma brasileira. Rio de Janeiro, Boletim da Divisão de Geologia e Mineralogia, Boletim 241, p 1-36. and Amaral (1974)Amaral G. 1974. Geologia Pré Cambriana da Região Amazônica. Tese de Doutorado, Instituto de Geociências, Universidade de São Paulo, 212 p., in which the Rio Apa Terrane is described as a prolongation of the Amazon Craton and the basement of Neoproterozoic mobile belts. This work adopted the second proposal thus considering the Rio Apa Terrane as a southern portion of the Amazon Craton (Fig. 1)

Based on geological and geochronological data, Lacerda Filho et al. (2006)Lacerda Filho J.W., Brito R.S.C., Silva M.G., Oliveira C.C. De, Moreton L.C., Martins E.G., Lopes R.C., Lima T.M., Larizzatti J.H., Valente C.R. 2006. Geologia e Recursos Minerais do Estado de Mato Grosso do Sul. Programa integração, atualização e difusão de dados de geologia do Brasil. Convênio CPRM/SICME - MS, MME, 10. 28 p. indicate that rocks from Rio Apa Province were formed between 1.95 and 1.75 Ga, which are further divided into three geotectonic compartments: Remnant Oceanic Crust (2.2 to 1.95 Ga), Rio Apa Magmatic Arc (1.95 to 1.87 Ga) and Amoguija Magmatic Arc (1.87 to 1.75 Ga). In addition to the units described and chronologically stacked in this work, these authors also describe the Mafic Continental Magmatism (1.79 to 1.78 Ga) and the Rio Perdido Mafic Dike Swarms (914 ± 9 Ma).

The Amoguija Magmatic Arc is comprised by the Alumiador Intrusive Suite and the Serra da Bocaina Formation. The term Alumiador Intrusive Suite, according to Lacerda Filho et al. (2006)Lacerda Filho J.W., Brito R.S.C., Silva M.G., Oliveira C.C. De, Moreton L.C., Martins E.G., Lopes R.C., Lima T.M., Larizzatti J.H., Valente C.R. 2006. Geologia e Recursos Minerais do Estado de Mato Grosso do Sul. Programa integração, atualização e difusão de dados de geologia do Brasil. Convênio CPRM/SICME - MS, MME, 10. 28 p., Godoy et al. (2010)Godoy A.M., Manzano J.C., Araújo L.M.B., Silva J.A. 2010. Suíte Vulcânica Serra da Bocaina, Grupo Amoguijá - Maciço Rio Apa - MS . São Paulo, UNESP, Geociências, 29:571-587. and Manzano et al. (2012)Manzano J.C., Godoy A.M., Araújo L.M.B., Godoy L.P. 2012. Suíte Plutônica Alumiador, Grupo Amonguijá, Maciço Rio Apa - MS São Paulo, UNESP . Geociências, 31(3):351-370., corresponds to a N-S trending elongated batholith of syeno to monzogranitic composition consisting of gray to pink leucocratic rocks, isotropic to anisotropic. Plens et al. (2013)Plens D.P., Ruiz A.S., Sousa M.Z.A.M., Batata E.F., Lafon J.M., Brittes A.F.N. 2013. Batólito Cerro Porã: granito tipo-A pós-orogênico do arco magmático Amoguijá - Terreno Rio Apa - sul do Cráton Amazônico. Brazilian Journal of Geology, 43(3):515-534. and Nogueira et al. (2013)Nogueira S. F., Sousa M. Z. A., Ruiz A. S., Batata M. E. F., Cabrera R. F., Costa J. T. 2013. Granito Aquidabã - Suíte Intrusiva Alumiador - Sul do Cráton Amazônico - Geologia, Petrografia e Geoquímica. In: Anais do Simpósio de Geologia da Amazônia, Belém, 13º, SBG-NO, Belém , p. 368-371. grouped the granitic intrusions of the Amoguija Magmatic Arc into the Alumiador Intrusive Suite.

Lacerda Filho et al. (2006)Lacerda Filho J.W., Brito R.S.C., Silva M.G., Oliveira C.C. De, Moreton L.C., Martins E.G., Lopes R.C., Lima T.M., Larizzatti J.H., Valente C.R. 2006. Geologia e Recursos Minerais do Estado de Mato Grosso do Sul. Programa integração, atualização e difusão de dados de geologia do Brasil. Convênio CPRM/SICME - MS, MME, 10. 28 p. obtained a SHRIMP U-Pb zircon crystallization age of 1,867 Ma from a porphyritic monzogranite and Sm-Nd isotopic data revealed a T_DM model age of 2.17 Ga and ε_Nd around -0.68, indicating a juvenile arc with some crustal contamination generated in continental margin settings. Cordani et al. (2010)Cordani U.G., Teixeira W., Tassinari, C.C.G., Ruiz A.S. 2010. The Rio Apa Craton in Mato Grosso do Sul (Brazil) and Northern Paraguay geochronological evolution, correlations and tectonic implications for Rodinia and Gondwana. American Journal of Science, 310:1-43. presented Ar-Ar and K-Ar data around 1,300 Ma for the volcanic rocks from Serra da Bocaina and plutonic rocks from Alumiador Intrusive Suite. Theses authors presented a U-Pb zircon age of 1,839 ± 33 Ma and Nd T_DM model ages between 2.54 and 2.49 Ga. Table 1 summarizes the geochronological data available for the Alumiador Intrusive Suite.

The San Pablo Terrane (Fig. 2) in Bolivia was first called Crystal Block by Litherland and Klink (1982)Litherland M. & Klinck B.A. 1982. Introducting the terms: "Paraguá Cráton" and "Pensamiento Granitoid Complex" for use in sheet reports . Rep East Bolivia Miner Expl Proj., Santa Cruz, ML/37 (Upublished). and posteriorly called San Pablo by Saes and Leite (1993)Saes G.S. & Leite J.A.D. 1993. Evolução tectono-sedimentar do Grupo Aguapeí, Proterozoico Médio na porção meridional do Cráton Amazônico: Mato Grosso e Oriente Boliviano . Revista Brasileira de Geociência, 23(1):31-37., Saes and Fragoso Cesar (1994Saes G.S. & Fragoso César A.R.S. 1994. The Aguapeí basin (Southwest Amazonia): A Grenville age aulacogen of the Sunsas orogeny. In: SBG, 38° Congresso Brasileiro de Geologia. Atas 1, 207-209., 1996Saes G.S.& Fragoso César A.R.S.1996. Acresção de terrenos mesoproterozoicos no SW da Amazônia. In: SBG, Congresso Brasileiro de Geologia, 39, Atas, p. 348.) and Saes (1999)Saes G.S.1999. Evolução Tectônica e Paleogeográfica do Aulacógeno Aguapeí (1.2-1.0 Ga) e dos Terrenos do seu Embasamento na Porção sul do Cráton Amazônico. Tese de Doutorado, Instituto de Geociências, Universidade de São Paulo, 135 p.. According to Saes (1999)Saes G.S.1999. Evolução Tectônica e Paleogeográfica do Aulacógeno Aguapeí (1.2-1.0 Ga) e dos Terrenos do seu Embasamento na Porção sul do Cráton Amazônico. Tese de Doutorado, Instituto de Geociências, Universidade de São Paulo, 135 p., the lack of Sunsas Group records in the Terrane would justify its individualization. The San Pablo Terrane is bordered by a tectonic discontinuity represented by the San Diablo Front (Litherland et al. 1986Litherland M., Annells R.N., Appleton J.D., Berrangé J.P., Bloomfield K., Burton C.C.J., Darbyshire D.P.F., Fletcher C.J.N., Hawkins M.P.,. Klinck B.A, Lanos A., Mithcell W.I., O Connor E.A., Pitfield P.E.J., Power G.E., Webb B.C. 1986. The Geology and Mineral Resources of the Bolivian Precambrian Shield. British Geological Survey. Overseas Memoir 9. London: Her Majesty's Stationery Office. 140 p.) or San Diablo Straightening Zone (Pitfield et al. 1979, inSaes 1999Saes G.S.1999. Evolução Tectônica e Paleogeográfica do Aulacógeno Aguapeí (1.2-1.0 Ga) e dos Terrenos do seu Embasamento na Porção sul do Cráton Amazônico. Tese de Doutorado, Instituto de Geociências, Universidade de São Paulo, 135 p.)

For the Correreca Granite, Vargas-Mattos (2010)Vargas-Mattos G.L. 2010. Caracterização geocronológica e geoquímica dos granitos proterozoicos: implicação para a evolução crustal da borda SW do Cráton Amazônico na Bolívia. Tese de Doutorado, Faculdade de Geologia, Universidade do Estado do Rio de Janeiro, 164 p. obtained Pb-Pb zircon ages between 1,920 and 1,895 Ma, and Sm-Nd T_DM model ages between 2.8 and 2.9 Ga and ε_Nd(t) values of -8.5 and -9.4, which indicates a Paleoproterozoic felsic magmatism in the San Pablo Terrane. These results corroborate the existence of a crustal block on south of the Paragua Terrane, bordered by the San Diablo Shear Zone, as previously proposed by Litherland and Klink (1982)Litherland M. & Klinck B.A. 1982. Introducting the terms: "Paraguá Cráton" and "Pensamiento Granitoid Complex" for use in sheet reports . Rep East Bolivia Miner Expl Proj., Santa Cruz, ML/37 (Upublished). and posteriorly by Saes and Leite (1993)Saes G.S. & Leite J.A.D. 1993. Evolução tectono-sedimentar do Grupo Aguapeí, Proterozoico Médio na porção meridional do Cráton Amazônico: Mato Grosso e Oriente Boliviano . Revista Brasileira de Geociência, 23(1):31-37.. The Correreca Granite is located in the region of Rincon Del Tigre and Santo Corazon. It is a batholit overlain by sedimentary rocks of the Sunsas Group to the north, by the Boqui Group to the west, and by the Murcielago Group to the south. To the east, it is in fault contact with the Santo Corazon Granitoid Complex.

FIELD AND PETROGRAPHIC ASPECTS

The Taquaral Granite crops out as large and small blocks, massive or weakly foliated and, sometimes, as mylonitic truncated by cataclastic bands, aplite and diabase dikes and pegmatitic pockets. It also occurs as felsic microgranular enclaves and xenoliths of quartz-diorite and amphibolite, respectively, which are rounded to ellipsoidal, centimetric to decametric. This unit is partially and tectonically overlain by sediments of the Urucum, Tamengo, Bocaina and Pantanal formations and by aluvionar deposits. The contact with the Urucum Formation is only tectonic but the Tamengo and Bocaina formations also partially overlain the granite unconformably.

The study of the Taquaral Granite and detailed geological mapping at a scale of 1:50.000 (Fig. 3) allowed recognize three petrographic facies where it is observed in the field that one facies encompasses another and these are then not discriminated at the mapped scale. The first facies is gray, medium- to coarse-grained (GMCF); the second facies is pink, coarse-grained (PCF) and the third facies is pink, fine-grained (PFF), all of which are massive or weakly foliated containing biotite and amphibole as the major mafic minerals.

Macroscopically, these facies are classified as hornblende-biotite-granitoids and plotted in QAP diagram (Streckeisen 1976Streckeisen A.L. 1976. To each plutonic rock its proper name. Earth Science Review, 12:1-33.; Fig. 4) as quartz-monzodiorites, granodiorites, quartz-monzonites, monzo and syenogranites.

The GMCF predominates volumetrically in the mapped body and is characterized by gray, inequigranular to equigranular medium- to coarse-grained leucocratic rocks, which are classified as quartz-monzodiorite, granodiorite and monzogranite (Figs. 4, 5A and 5B). Pegmatite pockets up to 4 m thick are observed. In the mylonitic portion of this facies, stretched and rotated alkali feldspar porphyroclasts occur in a fine- to medium-grained quartz-feldspathic groundmass which is classified as mylonite (Sibson 1977Sibson R.H. 1977. Fault rocks and fault mechanisms. Journal of the Geological Society, 133:191-213.), based on the relationship between porphyroclasts and groundmass.

The PCF is composed of pink, inequigranular coarse-grained leucocratic rocks, which are classified as quartz-monzonite and monzogranite (Fig. 4). This facies is distinguished from the others due to the presence of dark-pink subhedral crystals of alkali feldspar up to 3 cm in length (Figs. 5C and 5D).

The PPF consists of light-pink, equi- to inequigranular hololeucocratic rocks of monzo to syenogranite composition (Fig. 4). Aplite dikes occur predominantly as fine-grained rocks, up to 15 cm in thickness, in abrupt and reactive contacts with GMCF and PCF (Figs.5E and 5F).

Optically, rocks from the GMCF show hipidiomorphic to xenomorphic textures as well as inequigranular to locally graphic textures composed of plagioclase, quartz, alkali feldspar (microcline) and mafic minerals, which are identified as biotite, hornblende, and opaques. Accessory minerals are represented by titanite, apatite, allanite, opaques and zircon (Fig. 6). The mylonites have a fine- to medium-grained groundmass showing porphyroblastic to granoblastic textures. Felsic and mafic minerals are oriented, however they also occur surrounding alkali feldspar porphyroclasts. Quartz aggregates and recrystallized feldspar may occur bordering porphyroclasts and characterizing pressure shadow. This facies is strongly affected by sericitization, argilitization, saussuritization of feldspars, and chloritization of biotite and amphibole as a result of hydrothermal alteration.

Microscopically, rocks from the PCF usually displays hipidiomorphic to xenomorphic textures, and rarely graphic texture, consisting of alkali feldspar (perthitic microcline), plagioclase, quartz, biotite, and amphibole (hornblende) and having titanite, apatite, zircon, opaques as accessory minerals (Fig. 7). The rocks are strongly altered showing sericitized or saussuritized feldspars with dusty aspect, as well as chloritized biotite and amphibole.

Under the microscope, rocks from the PPF are predominantly equigranular having xenomorphic texture and consisting of alkali feldspar (microcline), quartz, plagioclase and less than 5% mafic minerals (biotite, hornblende, titanite, apatite and opaques; Figs. 8Aand 8B). It is weakly altered with products such as sericite, clay minerals, chlorite and epidote-group minerals, which may occur within micro-veins.

Two enclaves of distinct nature and origin were found in the Taquaral Granite. One of mafic composition corresponds to a xenolith and another is identified as microgranular felsic enclave (MFE) which represents the process of magma mingling (heterogeneous mixing). The xenoliths occurs volumetrically subordinate with amphibolitic composition, elongated, oval to rounded, ranging from centimeter to meter in size, and consisting of amphibole, plagioclase, opaque minerals and titanite. The centimeter-size MFE is rounded and consists of plagioclase, quartz, alkali feldspars and biotite. Typical features of magma mixing are observed in the MFE at macroscopic and microscopic scales, such as: reactive contact with the host rock, engulfment of xenocrystals, corroded quartz, poikilitic quartz engulfing biotite, hornblende, apatite, and opaque minerals and glomeroporphyros of plagioclase and biotite.

The centimeter- to meter-size dikes truncate the Taquaral Granite in abrupt contacts (Figs. 9A and 9B) and correspond to gabbroic rocks, which were classified as diabase based on grain size and occurrence. Macroscopically, these are massive, dark-gray to black, inequigranular very fine to fine-grained melanocratic rocks composed of variable proportions of plagioclase and mafic minerals (pyroxene, biotite and amphibole; Figs. 9Cand 9D).

STRUCTURAL ANALYSIS

In order to understand the structural evolution and the kinematics of deformation, which affected the Taquaral Granite, structural analysis was carried out in the study area (Fig. 3). The structural analysis follows the concept of deformation phases according to Sá and Hackspacher (1982)Sá E.F.J. & Hackspacher P.C. 1982. Revisão sobre análise estrutural, parte l - conceituação básica e métodos . Ciências da Terra, 5:24-36. while description and tectonic structures classification, such as foliations and lineations, are according to Passchier and Trouw (2005)Passchier C.W. & Trouw R.A.J. 2005. Microtectonics, 2nd ed., Germany, Springer-Verlag, 366 p.. Descriptive analysis of field-scale structures associated with examining satellite images and microscopic description allowed the identification of two deformation stages, here called F₁ and F₂.

Taquaral Granite does not display intense penetrative deformation and rocks are usually isotropic to weakly foliated. Mylonitic foliation is developed in ductile deformation zones, and cataclasites are widely observed in fault zones. The latter also affected the sedimentary covers of the Corumbá and Jacadigo Groups.

The first deformation phase (F₁) is responsible for the development of incipient penetrative foliation (S₁) being heterogeneous in intensity and orientation ( . 10A). A mylonitic banding is observed with development of protomylonites to mylonites indicating strong ductile deformation associated with phase F₁. Mylonitic foliation is parallel to the regional penetrative foliation (S1), both of them preferentially oriented to N20-30E, dipping 75°-85° towards the NW.

The rotated plagioclase porphyroclasts occur in a fine- to medium-grained groundmass forming a characteristic augen texture. Felsic and mafic minerals are preferentially oriented surrounding the porphyroclasts in the groundmass (Fig. 10 B).

S₁ measurements show small variations as illustrated in Fig. 11. S₁ field measurements show a maximum concentration at N10-20 E /80 to 90 NW.

Under the microscope, typical features of ductile deformation are observed, such as quartz ribbons, recrystallized grains of feldspars and quartz (Fig. 12A), kink bands in biotite, deformation twins in plagioclase, and rotated porphyroclasts (Fig. 12B).

The second deformation phase (F₂) is brittle, younger and posterior to the deposition of sedimentary covers of the Jacadigo and Corumbá Groups. This phase is responsible for the development of fault zones and cataclastic rocks, such as cataclasite, protocataclasite and rarely ultracataclasite.

Two regional faulting systems are identified: one with faults striking N50 to W20 and another with E-W trending faults, both dipping nearly vertically. However, the chronological succession of these structures is not established. The development of thick cataclastic bands is observed in the granitic basement as well as in the sedimentary covers. Cataclasites from the Taquaral Granite and Corumbá Group are products of brittle deformation (F₂) which formed a set of faults nucleating on the central portion and northwest of the study area. The fault rocks are classified as protocataclasites composed of angular to rounded fragments of granite, dolomitic limestone and diabase varying between 1 and 50 cm in a medium to coarse-grained groundmass of granitic composition and carbonate cemented. In general, the contacts between clasts and groundmass are observable (Fig. 13A). The cataclastic bands up to 10 cm thick occur cutting the Taquaral Granite. These bands are composed of angular to rounded grains of quartz, alkali feldspar and plagioclase varying from millimetres to 1-2 cm in a fine-grained groundmass, gray to pink in color. Percolation of hydrothermal fluids occurs parallel to the cataclastic bands leading to silicification, epidotization, chloritization and sericitization (Fig. 13B).

GEOCHEMICAL CHARACTERIZATION

Chemical data of the Taquaral Granite showed wide compositional variation from intermediate to acid rocks with silica content between 60.34 and 75.76% (Tab. 2); GMCF shows values between 60.34 and 61.55%; PCF between 65.47 and 68.64%, and PFF from 75.19 to 75.76 %. Harker diagrams (Fig. 14) indicate negative correlation for the elements TiO₂, Al₂O₃, Fe₂O₃ MgO, CaO and P₂O₅ versus SiO₂, which may suggest fractional crystallization.

Rocks from the Taquaral Granite are chemically classified as tonalites, granodiorites and syenogranites according to R1-R2 diagram by La Roche (1980La Roche H 1980 . Granites chemistry through multicationic diagrams. Sciences de la Terre, Série Informatique Géologique, 13:65-88.; Fig. 15A), and are similarly plotted as quartz monzonites, granites and granodiorite in the Q-P diagram (Debon & Le Fort 1983Debon F. & Le Fort P 1983. A chemical mineralogical classification of common plutonic rocks and associations. Trans. R. Soc. Edinburgh: Earth Science, 73:135-149.; Fig. 15B). Except for a sample plotted as quartz-monzonite, the granodioritic and granitic compositions are supported when using the classification based on normative feldspar in the Ab-An-Or diagram, which is applicable to rocks with normative quartz contents higher than 10% as proposed by O'Connor (1965)O'Connor J.T. 1965. A classification for quartz-rich igneous rocks based on feldspar ratios. US Geological Survey, 525B: 79-84. and modified by Barker (1979Barker O.B. 1979. A contribution to the geology of the Soutpansberg Group, Waterberg Supergroup, northern Transvaal. M. Sc. Thesis, Witwatersrand Univ., Johannesburg, 116 p.; Fig. 15C).

The Na₂O+K₂O-CaO versus SiO₂ diagram by Frost et al. (2001Frost B.R., Barnes C.G., Collins W.J., Arculus R.J., Elis D.J., Frost C.D. 2001. A Geochemical Classification for Granitic Rocks. Journal of Petrology, 42:2033-2048.; Fig. 16A) assigns to the Taquaral Granite a magnesian subalkaline magmatism, calc-alkaline type, enriched in alkalis. According to the diagram K₂O versus SiO₂ by Peccerillo and Taylor (1976Peccerillo R. & Taylor S. R 1976 . Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, northern Turkey. Contributions to Mineralogy and Petrology, 58: 63-81.; Fig. 16B), the granite showed medium to high potassium composition.

Excepting one PFF sample, rocks are magnesian granites in the FeOt/(FeOt+MgO) versus SiO₂ diagram (Fig. 16C) proposed by Frost et al. (2001)Frost B.R., Barnes C.G., Collins W.J., Arculus R.J., Elis D.J., Frost C.D. 2001. A Geochemical Classification for Granitic Rocks. Journal of Petrology, 42:2033-2048.. Most of them are classified as metaluminous rocks, however rocks of monzogranitic composition from the GMCF coincide with the peraluminous field in the diagram A/CNK versus A/NK by Maniar & Piccoli (1989Maniar P. D. & Piccoli P.M. 1989. Tectonic discrimination of granitoids. Geological Society American Bulletin, 101:635-643.; Fig. 16D) which is based on Shand's indexes.

The Taquaral Granite plots representatively within the Magmatic Arc field in the Rb versus Y+Nb (Fig. 17A) and Hf-Rb-Ta (Fig. 17B) diagrams proposed, respectively, by Pearce et al. (1984)Pearce J.A., Harris N.B.W., Tindle A.G. 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology, 25(4):956-983. and Harris et al. (1986)Harris N.B.W., Pearce J.A., Tindle A.G. 1986. Geochemical characteristics of collision-zone magmatism. In: Coward M.P. & Ries, A.C. (eds) Special Publications of Geological Society, London, 19:67-81..

Trace elements pattern associated with K₂O contents, normalized to Ocean Ridge Granites values from Pearce et al. (1984Pearce J.A., Harris N.B.W., Tindle A.G. 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology, 25(4):956-983.; Fig. 18A), shows enrichment in large-ion litophile elements (LILE) relative to high field strength elements (HFSE) with negative Nb and Ta anomalies, a typical pattern caused by crustal contribution (Rollinson 1993Rollinson H.R. 1993. Using geochemical data: evaluation, presentation, interpretation. Longman Geochemistry Series.) or subduction zone settings (Kelemen et al. 1993Kelemen P.B., Shimizu N., Dunn T. 1993. Relative depletion of niobium in some arc magmas and the continental crust: partitioning of K, Nb, La and Ce during melt/rock reaction in the upper mantle. Earth Planet Sci. Lett, 120:111-134.).

The contents of Rare Earth Elements (REE) of the Taquaral Granite show similar pattern to calc-alkaline granitoids with impoverishment of heavy REE relative to light REE when normalized to chondritic values from Sun and MacDonough (1989Sun S.S. & MacDonough W.F. 1989. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and process . Geological Society London, 1:1313-345.; Fig. 18B). Heavy REE show subhorizontal pattern with (Gd/Yb)_N ratios between 1.37 and 2.85, and a stronger light REE fractionation expressed by (La/Sm)_N ratio varying from 2.65 to 9.11. An even pattern is observed for the rocks from the GMCF with La/Yb ratios varying from 8.74 to 17.34; PCF samples show La/Yb variation between 11.63 and 28.85 while two PFF samples show distinct La/Yb ratios (16,69 and 47,14). Eu/Eu* ratio varies between 0.40 and 1.10 for the studied rocks. GMCF samples present this ratio between 0.74 and 1.10; PCF between 0.75 and 0.85, and PFF between 0.40 and 0.64. One of PFF samples show a strong negative Eu anomaly, however the same pattern for most of them. PFF samples show a vertical displacement due to lower contents of heavy REE indicating greater differentiation.

ISOTOPIC DATA

In order to obtain the crystallization age and characteristics of magmatism, which formed the Taquaral Granite, two samples were collected from the Taquaral Settlement, northeast part of the mapped body. The sample RM-07 (UTM 428893/7891896) was prepared for U-Pb zircon geochronology by SHRIMP and for whole-rock Sm-Nd isotopic analysis together with the sample RM-09A (UTM 429547/7891481). RM-07A belongs to the Gray Medium- to Coarse-grained Facies (GMCF) and RM-09A corresponds to the Pink Fine-grained Facies (PFF).

U-Pb zircon dating (SHRIMP)

Among the 150 zircon grains handpicked from RM-07, 10 (ten) grains were selected for U-Pb analyses. Most of the selected crystals displays short prism. Some crystals are elongated varying from 80 to 225 μm in length and showing a 3:1 length-width relationship. A few crystals are 1:1. Sometimes they occur fractured or broken, pink in color, varying from nearly incolor to dark.

Cathodoluminescence imaging (CL) of zircons shows relatively regular light and dark band zoning which is interpreted as a variation in U-content as differentiation occurs. The crystal 12.1 shows two growth phases displaying overgrowth rims (Fig. 19J).

The results are shown in Tab. 3. In the U-Pb Concordia diagram (Fig. 20), the zircon analyses furnished a concordant age of 1861 ± 5.3 Ma (1σ). Taking into consideration the magmatic features of the analysed grains, the age 1861 ± 5.3 Ma is interpreted as the crystallization age of the Taquaral Granite.

Sm-Nd isotopic analyses

Whole rock Sm-Nd analyses from the samples RM-07 and RM-09A show T_DM model ages of 2.32 and 2.25 Ga, and strongly negative ε_Nd(0) values of -20.05 and -22.98, respectively (Tab. 4). ε_Nd(t) values, calculated at a crystallization age of 1861 ± 5.3 Ma, using the U-Pb SHRIMP dating show values of -1.48 for sample RM-07 and -1.28 for sample RM-09A. ε_Nd(1,86Ga) negative values and T_DM model ages of 2.32 and 2.25 Ga indicate a Paleoproterozoic crustal source for both facies of the Taquaral Granite involving partial melting of Rhyacian continental crust.

DISCUSSION AND CONCLUSIONS

The basement underlying the Neoproterozoic sedimentary covers in the region of Corumba has been described by Araújo et al. (1982)Araújo H.J.T., Santos Neto A., Trindade C..H., Pinto J.C.A., Montalvão R.M.G., Dourado T.D.C., Palmeira R.C.B., Tassinari C.C.G. 1982. Folha SF. 21 - Campo Grande. In: Brasil. Ministério das Minas e Energia. Projeto RADAMBRASIL - Geologia, 28:23-124., Del'Arco et al. (1982)Del'Arco J.O., Silva R.H., Tarapanoff I., Freire F.A., Pereira L.G.M., Souza S.L., Luz J.S., Palmeira R.C.B., Tassinari, C.C.G. 1982. Geologia. In: Brasil. Ministério das Minas e Energia, Projeto RADAMBRASIL, Folha SE.21. Corumbá e Parte da Folha SE 20. Geologia, 27:25-160., Godoi et al. (2001)Godoi H.O., Martins E.G., Mello J.C.R., Scislewski G. 2001. Programa de Levantamentos Geológicos Básicos do Brasil - PLGB: folha SE.21-Y-D - Corumbá; Folha SF.21-V-B- Aldeia Tomázia; Folha SF.21-V-D - Porto Murtinho: escala 1:250 000. Brasília, CPRM, 88 p. and Lacerda Filho et al. (2006)Lacerda Filho J.W., Brito R.S.C., Silva M.G., Oliveira C.C. De, Moreton L.C., Martins E.G., Lopes R.C., Lima T.M., Larizzatti J.H., Valente C.R. 2006. Geologia e Recursos Minerais do Estado de Mato Grosso do Sul. Programa integração, atualização e difusão de dados de geologia do Brasil. Convênio CPRM/SICME - MS, MME, 10. 28 p. as an ensemble of gneisses, amphibolites, metagranites and granodiorites grouped into the Archean Rio Apa Complex. By using field, petrographic and geochronological data it is possible to redefine the basement in this region as a set of Orosirian batholitic granitic intrusions related to the Alumiador Intrusive Suite of Araújo et al. (1982)Araújo H.J.T., Santos Neto A., Trindade C..H., Pinto J.C.A., Montalvão R.M.G., Dourado T.D.C., Palmeira R.C.B., Tassinari C.C.G. 1982. Folha SF. 21 - Campo Grande. In: Brasil. Ministério das Minas e Energia. Projeto RADAMBRASIL - Geologia, 28:23-124..

Studying the Taquaral granite allows recognizing three petrographic facies: Gray Medium- to Coarse-grained Facies (GMCF), Pink Coarse-grained Facies (PCF) and Pink Fine-grained Facies (PFF); as well as two distinct types of enclaves in terms of nature and origin, one of them is an amphibolitic xenolith and the other, a felsic microgranular enclave (FME) having the composition of quartz-diorite. For the latter, an origin related to magma mingling is attributed according to macroscopic features, such as reactive contact with the host rock and engulfment of xenocrystals as well as microscopic features such as poikilitic quartz or corroded quartz, and glomeroporphyros of plagioclase and biotite. Hibbard (1991)Hibbard M.J. 1991. Textural anatomy of twelve magma-mixed granitoid systems. In: Didier J. & Barbarin B. (Eds.) Enclaves and granite petrology. Amsterdam: Elsevier,. p: 431-444. suggests that magma mingling is an important process of magmatic differentiation because it results from the interaction between melts of distinct compositions, temperature, density, viscosity and crystallization leading to the formation of hybrid rocks of intermediate composition.

Diabase dikes, which intrude the Taquaral Granite, are representative of an extensional regime. However, the lack of geochronological data is an obstacle in order to establish the igneous event in which these dikes were generated.

Two deformation phases are identified, a ductile phase (F₁) and a brittle phase (F₂). The first deformation phase F₁ developed penetrative foliation and NNE-trending shear zones dipping between 80° and 90° towards the NW. The structural pattern observed for the Taquaral Granite is not similar to the one observed for the Alumiador Intrusive Suite (Rio Apa Terrane) which in turn shows low-dipping foliations, usually lower than 40° towards the SE. Even though structural data from the Correreca Granite are scarce, a similar incipient foliation (Vargas-Mattos 2010Vargas-Mattos G.L. 2010. Caracterização geocronológica e geoquímica dos granitos proterozoicos: implicação para a evolução crustal da borda SW do Cráton Amazônico na Bolívia. Tese de Doutorado, Faculdade de Geologia, Universidade do Estado do Rio de Janeiro, 164 p.) to that of the Taquaral Granite is identified, however there are not enough measurements, making difficult to establish a structural correlation between these units. Kinematic analysis reveals that phase F₁ caused insignificant crustal shortening as a result of a NWW-SEE directed compressive stress leading to tectonic vergence towards the east-southeast. The second phase (F₂) affected both the basement granitic rocks as the rocks from the sedimentary covers represented by the Corumba and Jacadigo Groups causing the nucleation of a set of faults in the Taquaral Granite and Corumba Group and formation of cataclasites.

Phases F₁ and F₂ were generated during deformation stages at two different crustal levels. The first phase at crustal levels compatible with the greenschist facies settings and the second phase compatible with shallow crustal settings, likely related to either the evolution of Paraguay Belt and Tucavaca aulacogen or the evolution of Pantanal Basin.

The rocks grouped into the stratigraphic unit called Taquaral Granite are hornblende-biotite granitoids classified as quartz-monzodiorites, quartz-monzonites, granodiorites and monzo to syenogranites. They have intermediate to acidic composition and were generated in magmatic arc settings by a magnesian medium to high K calc-alkaline magmatism, metaluminous to peraluminous.

Isotopic data from the Taquaral Granite indicate a crystallization age of 1,861 ± 5 Ma (U-Pb SHRIMP). ε_{Nd (1,86Ga)} values of -1.48 and -1.28 and T_DM model ages of 2.32 and 2.25 Ga point out a crustal contribution to the magma, thus suggesting partial melting of continental crust.

This work dismisses the possibility that Taquaral Granite and Correreca Granite (San Pablo Terrane) are related to the same magmatic event once the latter shows older ages, between 1,925 and 1,894 Ma, and T_DM Archean ages between 2.8 and 2.9 Ga differing from the Ryacian model ages for the Taquaral Granite. Similarly, ε_Nd(t) values of -8.5 and -9.4 from the Correreca Granite differ significantly from the values obtained for the unit studied here.

Therefore we suggest a correlation between the Taquaral Granite and Alumiador Intrusive Suite (Rio Apa Terrane) once there display petrographic, compositional and age similarities between the Alumiador (Cordani et al. 2010Cordani U.G., Teixeira W., Tassinari, C.C.G., Ruiz A.S. 2010. The Rio Apa Craton in Mato Grosso do Sul (Brazil) and Northern Paraguay geochronological evolution, correlations and tectonic implications for Rodinia and Gondwana. American Journal of Science, 310:1-43.), despite their distinct T_DM model ages which suggest distinct crustal sources. Regarding the tectonic settings, the Taquaral Granite constitutes an intrusion related to convergent plate boundaries, continental magmatic arc, generated from magma-crust interaction. Considering a correlation between this intrusion and the plutons and batholiths from the Alumiador Intrusive Suite, thus we conclude that the Orosirian Amoguija Magmatic Arc (Lacerda Filho et al. 2006Lacerda Filho J.W., Brito R.S.C., Silva M.G., Oliveira C.C. De, Moreton L.C., Martins E.G., Lopes R.C., Lima T.M., Larizzatti J.H., Valente C.R. 2006. Geologia e Recursos Minerais do Estado de Mato Grosso do Sul. Programa integração, atualização e difusão de dados de geologia do Brasil. Convênio CPRM/SICME - MS, MME, 10. 28 p.) extends to the region of Corumba (MS), in the Brazil-Bolivia frontier.

ACKNOWLEDGMENTS

The authors acknowledge CAPES (PROCAD 096/2007), CNPq (479779/2011-2), Crustal and Tectonic Evolution Research Group "Guaporé" and the GEOCIAM (National Institute of Science and Geosciences Technology of the Amazon) for financial support in research development. The first author is grateful to CAPES for the concession of master's scholarship and to the Geoscience Postgraduate Program for supporting master studies.

REFERENCES

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